In the prior art there is a technique in radio communication systems called aggregation (see for example Non-patent References 1 and 2 below). Aggregation is a technique in which, for example, divided frequency bands (also called components) are combined into a band with broad bandwidth. Aggregation includes carrier aggregation, in which components in the same frequency bands (for example the 3.5 GHz band) are combined, and spectrum aggregation, in which components in different frequency bands (for example the 3.5 GHz band and the 2 GHz band) are combined.
As a conventional technique in a radio communication system, a technique regarding time intervals from the initial HS-DSCH (High-Speed Downlink Shared Channel) transmission to the next HS-DSCH transmission is disclosed (see for example Non-patent Reference 3 below).
Further, a conventional technique is disclosed in which a communication apparatus includes random access channel generation means for generating a random access channel formed from a preamble portion including at least a portion of control information, and transmission means for allocating to each user one among continuous frequency allocations and discontinuous combtooth frequency allocations, and for transmitting the random access channel using a variable multi-bandwidth (see for example Patent Reference 1 below).    Patent Reference 1: Japanese Laid-open Patent Publication No. 2006-311475    Non-patent Reference 1: 3GPP TR 36.814V1.3.0 (2009-June)    Non-patent Reference 2: R1-082468    Non-patent Reference 3: 3GPP TS 25.306V5.15.0 (2009-March)